feat(city): add airports, ATC agent, luminous signs, and AI model fallback chain

- Add two airports (north/south) with full geometry: runways, taxiways,
  aprons, terminals, hangars, stands, and helipads; walkable airport
  grounds extend beyond city bounds.
- Introduce ATC AI agent ("Torre de Controle City10") using AI_ATC_MODEL
  to generate takeoff clearances; includes dispatch endpoint with
  30-second cooldown and deterministic fallback on failure.
- Implement AI model fallback chain: preferred model → AI_FALLBACK_MODEL
  before failing, applied in ChatController and PersonTalkController.
- Add luminous sign labels (letreiros) for plazas, beach, food, hospital,
  school, city hall, and airports with day/night glow.
- Fix city presence cache: compute is_me per viewer instead of baking
  into shared per-second cache to prevent cross-user flag leakage.
- Add tests: AirportTest, CityPresenceTest, SignLabelsTest, and
  PersonTalkTest fallback model retry scenario.

tests/Feature/CityPresenceTest.php

@@ -0,0 +1,88 @@
+<?php
+
+namespace Tests\Feature;
+
+use App\Models\Character;
+use App\Models\User;
+use Database\Seeders\CityWorldSeeder;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+/**
+ * Presence feed correctness: the per-second rows are shared, but the
+ * is_me flag must always reflect the viewer of the current request —
+ * otherwise a citizen sees their own character as a remote player and
+ * the bump-to-talk chat opens with themselves.
+ */
+class CityPresenceTest extends TestCase
+{
+    use RefreshDatabase;
+
+    /**
+     * Boot world fixtures.
+     */
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->seed(CityWorldSeeder::class);
+    }
+
+    /**
+     * Two viewers polling within the same second each get their own
+     * is_me flags from the shared cache.
+     */
+    public function test_is_me_is_per_viewer_with_shared_cache(): void
+    {
+        [$userA, $charA] = $this->makeCitizen();
+        [$userB, $charB] = $this->makeCitizen();
+
+        // Viewer A seeds the shared per-second cache first.
+        $first = $this->actingAs($userA)
+            ->getJson('/city/presence')
+            ->assertOk()
+            ->json('citizens');
+
+        $this->assertTrue($this->flagFor($first, $charA->id), 'A must see itself as me');
+        $this->assertFalse($this->flagFor($first, $charB->id), 'A must not see B as me');
+
+        // Viewer B hits the SAME cache entry moments later.
+        $second = $this->actingAs($userB)
+            ->getJson('/city/presence')
+            ->assertOk()
+            ->json('citizens');
+
+        $this->assertTrue($this->flagFor($second, $charB->id), 'B must see itself as me');
+        $this->assertFalse($this->flagFor($second, $charA->id), 'B must not see A as me');
+    }
+
+    /**
+     * Create an active user paired with its in-world character.
+     *
+     * @return array{0: User, 1: Character}
+     */
+    private function makeCitizen(): array
+    {
+        $user = User::factory()->create([
+            'status' => User::STATUS_ACTIVE,
+            'is_active' => true,
+        ]);
+
+        return [$user, Character::ensureForUser($user)];
+    }
+
+    /**
+     * Extract the is_me flag for a character id from a presence payload.
+     *
+     * @param  list<array<string, mixed>>  $citizens
+     */
+    private function flagFor(array $citizens, int $characterId): bool
+    {
+        foreach ($citizens as $c) {
+            if ((int) $c['id'] === $characterId) {
+                return (bool) $c['is_me'];
+            }
+        }
+
+        $this->fail("Character {$characterId} missing from presence payload");
+    }
+}